Frequency addition and subtraction by means of auxiliary deflection electrodes in a cathode ray tube



O. E. H. RYDBECK EI'AL March 7, 1961 FREQUENCY ADDITION AND SUBTRACTION BY MEANS OF AUXILIARY DEFLECTION ELECTRODES IN A CATHODE RAY TUBE Filed April 29, 1957 2 Sheets-Sheet 1 mve mbas Olof Erik Hgns'Rydbeck Curl Morten Eugen Sienhqr dt ATTORNEYS March 7, 1961 o. E. H. RYDBECK ETAL 2,974,295

FREQUENCY ADDITION AND SUBTRACTION BY MEANS OF AUXILIARY DEF'LECTION ELECTRODES IN A CATHODE RAY TUBE 2 Sheets-Sheet 2 Filed April 29, 1957 INVENTORS Olof Erik Hons Rydbeck Curl Morten Eugen Stenhordt ATTORNEYS FREQUENCY ADDITION AND SUBTRACT ION BY MEANS OF AUXILIARY DEFL'ECTION ELEC- TRODES IN A CATHODE RAY TUBE Olof Erik Hans Rydbeck, Goteborg, Sweden (Fjaras,

Sweden), and Carl Marten Eugen Stenhardt, Langseleringen 28, Vallingby, Sweden This invention relates to an electronic apparatus utilizing a cathode ray, the main purpose of which is to obtain frequency addition and frequency subtraction and frequency multiplication of electricalsignals.

It has been proposed to obtain frequency multiplication by means of a cathode ray tube, the electron beam of which is deflected so as to describe a circular track on a target electrode. In front of said target electrode another electrode is disposed, said last mentioned electrode being provided with a number of apertures regularly displaced along the path that is swept by the electron beam. If the angular sweep frequency of the electron beam is o and the number of regularly spaced apertures is n, an alternating voltage of the angular frequency n-w will appear between the target electrode and the apertured electrode.

According to this invention the general operating principle of this known arrangement can be utilized for obtaining further effects such as frequency addition, fre-' quency subtraction or frequency modulation. 1

Other objects of the invention will appear from the following description, with references to the accompanying drawings, in which:

Fig. 1 illustrates a frequency multiplying electronic arrangement of a known construction,

means of which frequency addition or frequency subtraction together with frequency multiplication can be obtained, and

Fig. 3 illustrates a detail of the arrangement of Fig. 2 on a greater scale.

In Fig. 1 E designates an electron gun with a cathode K, a. control grid G, accelerating electrodes A and A two'pairs of deflection'electrodes D and D anapertured plate S and a target electrode S The system comprising these elements is enclosed in a glass tube 109 It is assumed that the two pairsof deflection plates are supplied with voltages of the same frequencybut-with a phase difierencelof 90. The electron beam'B thereby isdeflected so as'to make a circular sweepin the one orthe other direction. By means of potentiometers P andwP connecwd to the input terminals 5, 6 and 8, 9, respectively, for the deflection voltagethis voltage can be suitably. adjusted. Two capacitors Oi and Cd are used'for enabling a DC. voltageto be supplied to o'n'e deflection plate in each pair, for the purpose of adjusting the locationof the center point of the circular sweep. i The plate S is provided with apertures H and is. so located in the tube that the electron beam during its sweep passes, said apertures one after another, said ape crtures being regularly spaced a'ndlocalte'd at the same distance from the center of the plate S When the beam. passes one of the apertures H and strikes the collectorelectrode S 21 current pulse will pass from the plate S to, the collector electrode S lfvthe angular frequency of the deflection voltage is bifzlndthe "number of aperturesinthe plate S is an aren' A.C. voltage with an angular frequency equal to 21-10 I Fig. 2 shows a device according to the invention by will appear between the plates S and S 7 Between the plates S and S a tank circuit is connected comprising a transformer T with a primary winding L and a secondary winding L the latter being tuned by means of a capacitor C In series with the primary winding L a capacitor CS is connected which is intended to be a blocking condenser.

If it is assumed that the apertured plate S in the arrangement according to Fig. l is rotatable and if the angular frequency of rotation is equal to the angular sweep frequency of the electron beam and rotation is taking place in the same direction as the sweep, the frequency obtained from the collector plate will be zero.

If the apertured plate is rotating in the opposite direction but with the same angular frequency as the angular sweep frequency a a voltage with an angular fre-' quency of 211-01 will appear between the plates S and S If the angular frequency of rotation of the plate S is (0 the angular frequency of the voltage between S and S will be n(w w if the direction of the rotation is the same as the direction of the sweep and n(w +w if the relative directions of rotation are opposite.

The rotatable plate S can be considered as a suppress ing means with n suppressing and n non-suppressing parts, regularly distributed along the sweep path of the electron beam, said suppressing means being movable with a periodicity with the angular frequency m It may be advantageous to avoid mechanically mov able parts within an evacuated tube, and, therefore, the rotatable plate S can be replaced by a rotating deflection field, serving as a suppressing means as described.

Fig. 2 illustrates an embodiment of the invention in which means are provided for producing such a deflection field. Instead of the plates S S in the device according to Fig. l an electrode system is employed, comprising a central circular plate or the like, S an annular member 8,, arranged concentrically about said plate, and a collector electrode S arranged behind S and S Between S and 8,, there is an annular gap with a certain, suitable depth in the direction of the electron beam, through which gap the electron beam can pass when it is performing a circular sweep. The annular member 8,, comprises a plurality of electrode plates H insulated from each other and arranged side by side When the beam is passing through the gap during its circular sweep it will be influenced by any existing voltage between the plates H and the plate S whereby it will be deflected towards the plate S or towards the plates H A voltage of the order of, say 6 volts between the plate S and the plates H, may be required for a complete deflection of the electron beam so that it will not strike the plate S In case no such voltage exists the electron beam will pass through the gap without being disturbed by any influence. In the case just mentioned, Where a complete deviation is obtained with a voltage of 6 volts, it can be assumed that about half that deviation will be obtained with a voltage of 3 volts whereby one half of the electron beam will impinge upon either of the plates S or the plates H While the other half will pass through the gap 130. If, therefore a bias of 3 volts DC. is superposed on an alternating voltage of 3 volts the electron beam will oscillate in a radial direction. At maximum phase of the alternating voltage the beam will strike the plate S and at minimum phase it will pass freely through the gap 136 without striking any of the plates. Though a plurality of other possibilities of control are possible, only those cases will now be considered said voltage is totally deflected from the gap 130' and at minimum phase freely passes said gap, whereby the,

Patented 'Mar. 7, 1961 effects obtained with the arrangement according to Figs. 2 and 3 will be studied. 1

The electrodes I-I are connected in a multiphase circuit as shown in Fig. 2 whereby adjacent plates are connected to different phases of a multiphase system which in Fig. 2 is shown as a 6-phase system although any other number of phases can be used. The passing of the electron beam through the annular gap .130 will now vary depending on the multiphase voltage, for example in a manner such as is illustrated by the curve 140 in Fig. 3. At a certain moment on the plate H the deflection of the beam in an outward direction is maximum and in this case it is assumed that the beam passes freely through the annular gap 130 and strikes the plate S while simultaneously at the plate H the deflection inwardly is maximum, whereby the electron beam entirely strikes the plate S According to Fig. 2 the electrode arrangement is inserted in a tube 150 which tube further comprises an electron gun E and deflection plates D and D The deflection plates are connected to transformers T T each of which is connected to a source of alternating voltage with an angular frequency for imparting a circular sweep to the electron beam. The plates H, of the annular member S are connected in a 6-phase circuit, of which the phases 1, II and III are shown in the figure. The collector plate S is connected to a tank circuit comprising coils L and L and an adjustable condenser C The coil L is connected to terminals 52 and 53, which are the output terminals of the circuit.

The multiphase voltage generator circuit comprises an axiliary cathode ray tube 151, the target electrode of which is divided in a number of sectors P P -P corresponding to the number of phases. Further, this tube comprises an electron gun E and two pairs of deflection plates D and D for imparting a circular deflection to the electron beam. The sectors P --P are connected to coils l l respectively, in a multiphase circuit.

The deflection plates D and D are adjustably connected to the secondary sides of transformers T T the primary sides of which are connected to sources for deflection voltages of 'a frequency m for producing a circular sweep, whereby a pole changer SW is connected to the primary winding of the transformer T In operation, when the electron beam sweeps over the sectors P to P of the tube 151 a 6-phase voltage will be supplied to the coils l l From connecting contacts of the coils 1 -1,, connections are made to corresponding phases of the multiphase circuit in which the plates H are included, said connections being made via condensers C C etc. via suitable amplifiers F, as the voltage that can be obtained from the coils l l will be too low to deflect the electron beam in the tube 150.

4 rapidity of Rb revolutions per second, Rb being determined by the equation:

Rbh 21r where (.0 is the angular frequency of the deflection voltage applied to the deflection plates D and D of the tube 150.

If it is assumed that Rf=Rb, Le.

and that the direction of rotation of the beam and the multiphase field is the same, a substantially constant output voltage from the plate S in the tube 150 will be obtained, the magnitude of said output voltage being dependent on the bias voltage applied to the ter minals and 56. If, on the other hand,

differs from o an output voltage is obtained with an angular frequency that is proportional to if the alternating field produced by the plates H has a direction of rotation that is opposite to the rotational direction of the sweep in the tube 150, and proportional to 4.2 on n if the atternating field is rotating in the same direction as the sweep in the tube 150.

The original intention with the arrangement according to Figs. 2 and 3 was to enable a displacement of a carrier wave to be made upwards or downwards in respect of its frequency. Inthis case Ira is meant to be the fundamental angular frequency of the carrier wave while (0 is meant to be the figure by which it is desiredto displace that carrier wave in one or the other direction. With the, arrangement according to Fig. 2 it will be possible to achieve such displacement simply by operating the switch SW, said displacement being from the angular frequency and vice versa.

It is evident that by means of the circuit according to Fig. 2 it is possible to obtain frequency multiplication A DC. bias voltage is applied to the plates H via terminals 55, 56 and resistors R By changing the phase 180 by means of the switch SW connected to the plates D it is possible to reverse the direction of rotation of the sweep of the electron beam. The field of the 6-phase system will then rotate in an opposite directionthan before the reversal.

The multiphase field between the plates H and the electrode S in Fig. 2 is rotating with a rapidity of Rf revolutions per second, whereby as well as frequency addition and frequency subtraction. If a 6-phase system is chosen and it is desired to multiply by 12, there must be 12 6=72 plates H With such a tube it is of course possible to connect the electrodes H together in. some other way than has been assumed above. connected together two and two, a frequency multiplica tion with the factor 6 instead of 12 will be achieved. If theplates are connected together four and four 'a frequencymultiplication with the factor 3 will be obtained. Further, it may be observed that if a four phase system instead of a 6 phase system is used, it is possible to. connect the 72 plates in such way that 18 plates If for example, the plates are In this case, however,

As will be evident to anyone skilled in the art a grea't number of other modifications of the invention can be made without departing from the main principle of the same.

We claim: I

1. An electronic apparatus for obtaining frequency addition or frequency subtraction of two frequencies f; and f said apparatus comprising a tube, an electron gun for generating an electron beam within said tube, first deflecting means in said tube for imparting a peri- 'odic deflection of said beam in a predetermined, periodical sweep along a closed sweep path with a frequency of 1; cycles per second, a target electrode in said tube, a plurality of auxiliary deflecting means located near said target electrode between said first deflection means and said target electrode, said auxiliary deflection means being symmetrically disposed along said closed sweep path and being divided into m groups each having n auxiliary deflection means therein, where m is an integer greater than 1 but less than the number of auxiliary deflection means, the deflection means of each of the groups of such deflection means being interspersed among the auxiliary deflection means of the other groups, a source of multiphase energy having a frequency f and m phases, connecting means connecting each phase of said source to a diiferent one of said groups of deflection means for producing an auxiliary deflection field having m phases and n pole pairs, said auxiliary deflection field moving along said deflection path at a frequency of f /n cycles per second, said auxiliary deflection field causing a periodical auxiliary deflection of said beam to and from said target electrode during its sweep along said closed path, and a tank circuit tunable to the frequencies n-h-l-f or n- -f for deriving an alternating output energy from said target electrode of the frequency of n-hif cycles per second.

2. An electronic apparatus for obtaining frequency ad dition or frequency subtraction of two frequencies f; and 12,, said apparatus comprising a tube, an electron gun for generating an electron beam within said tube, first deflecting means in said tube for imparting a periodic deflection of said beam in a predetermined, periodical sweep along a closed sweep path with a frequency of f cycles per second, a target electrode in said tube, a

plurality of auxiliary deflecting means located near said target electrode between said first deflection means and said target electrode, said auxiliary deflection means being symmetrically disposed along said closed sweep path and being divided into m groups each having n auxiliary deflection means therein, where m is an integer greater than 1 but less than the number of auxiliary deflection means, the deflection means of each of the groups of such deflection means being interspersed among the auxiliary deflection means of the other groups, a source of multiphase energy having a frequency f and m phases, connecting means connecting each phase of said source to a different one of said groups of deflection means for producing an auxiliary deflection field having m phases and n pole pairs, said auxiliary deflection field moving along said deflection path at a frequency of 73/ n cycles per secnd, said auxiliary deflection field causing a periodical auxiliary deflection of said beam to and from said target electrode during its sweep along said closed path, and a tank circuit tunable to the frequencies nf +f or mi -f for deriving an alternating output energy from said target electrode of the frequency of n-hif cycles per second, and means for reversing the relative direction of movement of the beam and the auxiliary deflection field along said sweep path.

3. An electronic apparatus for obtaining frequency addition and frequency subtraction, said apparatus comprising a tube, an electron gun for generating an electron beam in said tube, first deflection meansin said tube for imparting a periodic deflection of said beam along a predetermined circular sweep path, said first deflec- 6 l tion means comprising two pairs or deflection member's arranged to deflect said beam in directions at an angle of to each other, a two phase alternating energy supply source, each of said deflection means being connected to a different one of the phases of said two phase alternating energy supply source, said source having a frequency of f cycles per second, a target electrode in said tube located in said sweep path, a plurality of auxiliary deflecting members symmetrically arranged around said sweep path between said first deflecting means and said target electrode, said deflection members being divided into m groups each having n auxiliary deflection means therein, where m is an integer greater than 1 but less than the number of auxiliary deflecting members, the deflecting members of each of said groups being symmetrically disposed alongsaid sweep path and the de fleeting members of each group being interspersed among theauxiliary deflecting members of the other groups, a source of multiphase energy having m phases and a frequency of f cycles per second, connecting means connecting each phase of said source of multiphase energy to all deflecting members of one of said groups of deflecting members for producing a rotating auxiliary deflection field within said tube, said auxiliary deflection field having m phases and n pole pairs, said auxiliary deflection field rotating around a path which is concentric to said circular deflection path, the speed of rotating of said auxiliary deflecting field being f /n revolutions per second, said auxiliary deflection field causing a periodical auxiliary deflection of said beam to and from said target electrode during its sweep along said path, and a tank circuit tunable to the frequencies nf +f or n-h-f for deriving an alternating output energy from said target electrode of the frequency of n-f i-f 4. An electronic apparatus for obtaining frequency addition and frequency subtraction, said apparatus comprising a tube, an electron gun for generating an electron beam in said tube, first deflection means in said tube for imparting a periodic deflection of said beam along a predetermined circular sweep path, said first deflection means comprising two pairs of deflection members arranged to deflect said beam in directions at an angle of 90 to each other, a two phase alternating energy supply source, each of said deflection means being connected to a different one of the phases of said two phase alternating energy supply source, said source having a frequency of f cycles per second, a target electrode in said tube located in said sweep path, a plurality of auxiliary deflecting members symmetrically arranged around said sweep path between said first deflecting means and said target electrode, said deflection members being divided into m groups each having n auxiliary deflection means therein, where m is an integer greater than 1 but less than the number of auxiliary deflecting members, the deflecting members of each of said groups being symmetrically disposed along said sweep path and the deflecting members of each group being interspersed among the auxiliary deflecting members of the other groups, a source of multiphase energy having m phases and a frequency of f cycles per second, connecting means connecting each phase of said source of multiphase energy to all deflecting members of one of said groups of deflecting members for producing a rotating auxiliary deflection field within said tube, said auxiliary deflection field having m phases and n pole pairs, said auxiliary deflection field rotating around a path which is concentric to said circular deflection path, the speed of rotating of said auxiliary deflecting field being f n revolutions per second, said auxiliary deflection field causing a periodical auxiliary deflection of said beam to and from said target electrode during its sweep along said path, and a tank circuit tunable to the frequencies n -f +f or n -f f for deriving an alternating output energy from said target electrode of the frequency of n-f if and means for reversing the relative direction of rotational movement of said beam along said sweep path and said rotating auxiliary deflection field.

5. An electronic apparatus for adding or subtracting a first and a second frequency, said apparatus comprising a tube, an electron gun in said tube for generating. an electron beam, means for deflecting said electron beam along a circular sweep path with a periodicity correspond ing to said first frequency, a target electrode in said tube, means for generating a rotatable, multipole, multiphase deflection field within said tube between said electron gun and said target electrode with a rotational axis coinciding with the axis of said circular sweep path for deflecting said electron beam to and from said target electrode during its sweep along said sweep path, means for rotating said multiphase deflection field with a rotational speed corresponding to said second frequency divided with the number of pole pairs of said multipole, multiphase deflection field, means for deriving from said target electrode an output energy ofa frequency which is the sum or the diflerence of said first frequency multiplied with the numher of pole pairsof said multipole, multiphase deflection field and said second frequency, and means for reversing the relative direction of rotation of said beam along said sweep path and said multiphase, multipole deflecting field.

References Cited in the file of this patent UNITED STATES PATENTS 

